People may encounter situations where they need to allow another person to enter their home or perform some action on their behalf. For example, a homeowner may wish to allow an electrician to access her home while she is away. To do so, the homeowner may have to leave a key under the doormat or have a neighbor let the electrician in. Such approaches may be disadvantageous, as they are not well-controlled and are vulnerable to abuse. For example, the neighbor may be unable to verify whether the electrician should be allowed to enter the house unless they talked to the homeowner themselves. Therefore, a better authentication and authorization process would be desirable.